Formaldehyde-free sizing composition for fibres, in particular mineral fibres, and resulting products

ABSTRACT

A formaldehyde-free sizing composition for products based on fibers, in particular mineral fibers, such as glass or rock fibers, which includes at least one reducing sugar, at least one inorganic acid metal salt, at least one amine, and at least one compound including activated ethylenic unsaturation(s), the inorganic acid metal salt being present in an amount at least equal to 1% of the weight of the reducing sugar.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is the U.S. National Stage of PCT/FR2012/051182, filedMay 25, 2012, which in turn claims priority to French Application No.1154547, filed May 25, 2011. The content of both applications areincorporated herein by reference in their entirety.

The present invention relates to the field of products based on fibres,in particular mineral fibres, bonded by a formaldehyde-free binder.

Very particularly, the invention relates to thermal and/or acousticinsulating products, the fibres of which are in the form of mineralwool, in particular of glass or of rock.

The manufacture of insulating products based on mineral wool generallycomprises a stage of manufacture of the wool itself, which can becarried out by various processes, for example according to the knowntechnique of fiberizing by internal or external centrifugation.

Internal centrifugation consists in introducing the molten material(generally glass or a rock) into a centrifugal device comprising amultitude of small orifices, the material being projected toward theperipheral wall of the device under the action of the centrifugal forceand escaping therefrom in the form of filaments. On leaving thecentrifugal device, the filaments are drawn and carried toward areceiving member by a gas stream having a high temperature and a highspeed, in order to form a web of fibres (or mineral wool).

External centrifugation consists, for its part, in pouring out themolten material at the external peripheral surface of rotating members,known as rotors, from where the said material is ejected under theaction of the centrifugal force. Means for drawing by gas stream and forcollecting on a receiving member are also provided.

In order to provide for the assembly of the fibres together and to makeit possible for the web to have cohesion, a sizing compositioncomprising a thermosetting resin is applied to the fibres, on the routebetween the outlet of the centrifugal device and the receiving member.The web of fibres coated with the size is subjected to a heat treatment,at a temperature generally of greater than 100° C., in order to bringabout the polycondensation of the resin and to thus obtain a thermaland/or acoustic insulating product having specific properties, inparticular dimensional stability, tensile strength, thickness recoveryafter compression and homogeneous colour.

The sizing composition to be projected onto the mineral wool isgenerally provided in the form of an aqueous solution including thethermosetting resin and additives, such as a catalyst for thecrosslinking of the resin, an adhesion-promoting silane, adust-preventing mineral oil, and the like. The sizing composition isgenerally applied to the fibres by spraying.

The properties of the sizing composition depend largely on thecharacteristics of the resin. From the viewpoint of the application, itis necessary for the sizing composition to exhibit good sprayability andto be able to be deposited at the surface of the fibres in order toefficiently bind them.

The resin has to be stable for a given period of time before being usedto form the sizing composition, which composition is generally preparedat the time of use by mixing the resin and the additives mentionedabove.

At the regulatory level, it is necessary for the resin to be regarded asnon-polluting, that is to say for it to comprise—and for it to generateduring the sizing stage or subsequently—as small an amount as possibleof compounds which may be harmful to human health or to the environment.

The thermosetting resins most commonly used are phenolic resinsbelonging to the family of the resols. In addition to their goodcrosslinkability under the abovementioned thermal conditions, theseresins are soluble in water, have a good affinity for mineral fibres, inparticular glass fibres, and are relatively inexpensive.

These resols are obtained by condensation of phenol and formaldehyde, inthe presence of a basic catalyst, in a formaldehyde/phenol molar ratioof greater than 1, so as to promote the reaction between the phenol andthe formaldehyde and to reduce the level of residual phenol in theresin. The condensation reaction between the phenol and the formaldehydeis carried out while limiting the degree of condensation of themonomers, in order to avoid the formation of long, relativelywater-insoluble, chains which reduce the dilutability. Consequently, theresin comprises a certain proportion of unreacted monomer, in particularformaldehyde, the presence of which is undesirable because of its knownharmful effects.

For this reason, resol-based resins are generally treated with urea,which reacts with the free formaldehyde by trapping it in the form ofnonvolatile urea-formaldehyde condensates. The presence of urea in theresin in addition brings a certain economic advantage as a result of itslow cost because it is possible to introduce it in a relatively largeamount without affecting the operating qualities of the resin, inparticular without harming the mechanical properties of the finalproduct, which significantly lowers the total cost of the resin.

Nevertheless, it has been observed that, under the temperatureconditions to which the web is subjected in order to obtain crosslinkingof the resin, the urea-formaldehyde condensates are not stable; theydecompose with restoration of the formaldehyde and urea (in its turn atleast partially decomposed to give ammonia), which are released into theatmosphere of the factory.

Regulations with regard to environmental protection, which are becomingmore restrictive, are forcing manufacturers of insulating products tolook for solutions which make it possible to further lower the levels ofundesirable emissions, in particular of formaldehyde.

Solutions in which resols are replaced in sizing compositions are known.

A first solution is based on the use of a carboxylic acid polymer, inparticular an acrylic acid polymer.

In U.S. Pat. No. 5,340,868, the size comprises a polycarboxylic polymer,a β-hydroxyamide and an at least trifunctional monomeric carboxylicacid.

Other sizing compositions have been provided which comprise apolycarboxylic polymer, a polyol and a catalyst, this catalyst beingable to be a phosphorus-comprising compound (U.S. Pat. No. 5,318,990,U.S. Pat. No. 5,661,213, U.S. Pat. No. 6,331,350, US 2003/0008978), afluoroborate (U.S. Pat. No. 5,977,232) or else a cyanamide, adicyanamide or a cyanoguanidine (U.S. Pat. No. 5,932,689).

The sizing compositions based on a polycarboxylic polymer and on apolyol can additionally comprise a cationic, amphoteric or nonionicsurfactant (US 2002/0188055), a coupling agent of silane type (US2004/0002567) or a dextrin as cobinder (US 2005/0215153).

A description has also been given of sizing compositions comprising analkanolamine including at least two hydroxyl groups and a polycarboxylicpolymer (U.S. Pat. No. 6,071,994, U.S. Pat. No. 6,099,773, U.S. Pat. No.6,146,746) in combination with a copolymer (U.S. Pat. No. 6,299,936).

A second solution in which resols are replaced is based on thecombination of a saccharide and a polycarboxylic acid.

In U.S. Pat. No. 5,895,804, a description is given of an adhesivecomposition based on heat-crosslinkable polysaccharides which can beused as size for mineral wool. The combination includes a polycarboxylicpolymer having at least two carboxylic acid functional groups and amolecular weight at least equal to 1000, and a polysaccharide having amolecular weight at least equal to 10 000.

In WO 2009/080938, the sizing composition comprises a monosaccharideand/or a polysaccharide and an organic polycarboxylic acid with a molarmass of less than 1000.

A formaldehyde-free aqueous sizing composition which comprises aMaillard reaction product, in particular combining a reducing sugar, acarboxylic acid and aqueous ammonia (WO 2007/014236), is also known. InWO 2009/019232 and WO 2009/019235, the proposal is made to substitute,for the carboxylic acid, an acid precursor derived from an inorganicsalt, in particular an ammonium salt, which exhibits the additionaladvantage of being able to replace all or part of the aqueous ammonia.

In WO 2011/019590 and WO 2011/019597, a description is given of aninsulating mat based on glass fibres which can be used in roofing. Thefibres are bonded by a sizing composition which comprises an inorganicacid salt and an aldehyde or a ketone. The inorganic acid salt isobtained by reaction of an inorganic acid and aqueous ammonia or apolyamine.

In WO 2011/019593 and WO 2011/019598, the abovementioned insulating matis obtained from a sizing composition which comprises an amino amide andan aldehyde or a ketone. The amino amide is obtained by reaction of apolyfunctional primary or secondary amine and a saturated or unsaturatedreactant, such as a carboxylic acid, an acid anhydride or a derivative(ester or a salt) of these compounds.

There exists a need to have available novel formaldehyde-free sizingcompositions which make it possible to manufacture products based onfibres, in particular mineral fibres, which can be used as acousticand/or thermal insulators.

The aim of the present invention is to provide an alternative to theformaldehyde-free sizing compositions for fibres, in particular mineralfibres.

This aim is achieved by the sizing composition in accordance with theinvention, which comprises:

-   -   at least one reducing sugar,    -   at least one inorganic acid metal salt,    -   at least one amine,    -   and at least one compound comprising activated ethylenic        unsaturation(s),

the inorganic acid metal salt being present in an amount at least equalto 1% of the weight of the reducing sugar.

The reducing sugar in accordance with the present invention is anoligosaccharide including from 1 to 10 saccharide units, preferably atmost 5.

Mention may be made, as examples of monosaccharides, such as glucose,galactose or mannose, or disaccharides, such as fructose, lactose,maltose, isomaltose and cellobiose. Preference is given to glucose andfructose, advantageously to glucose.

The inorganic acid metal salt act as agent for the dehydration of thereducing sugar and it must make possible the formation of a systemcomprising at least two conjugated ethylenic bonds.

The inorganic acid metal salt is chosen from inorganic acid alkalimetal, alkaline earth metal, transition metal and poor metal salts.Preferably, it is a sodium, magnesium, iron, cobalt, nickel, copper,zinc or aluminium salt, advantageously a copper, iron(II), aluminium orzinc salt.

The inorganic acid metal salt is preferably chosen from sulphates,chlorides, nitrates, phosphates and carbonates and advantageously fromsulphates and chlorides.

Preference is given to copper sulphate, iron(II) sulphate, zincsulphate, aluminium sulphate, potassium aluminium sulphate (or potassiumalum) and aluminium chloride, in particular to copper sulphate andaluminium sulphate.

In the sizing composition, the amount of inorganic acid metal saltrepresents at most 30% of the weight of the reducing sugar, preferablyfrom 5 to 25% and advantageously from 10 to 20%.

The amine in accordance with the invention corresponds to the followingformula (I):R-A-NHR₁  (I)

in which:

-   -   R is equal to H, OH, NHR₁ or —NR₁,    -   A represents an optionally branched alkylene, arylalkylene,        arylene or alkylarylene group, a —CO— group or a group of        following formula (II):

-   -   in which:        -   X is equal to —O— or —NR₂—            -   with R₂ equal to H, —(CH₂)_(z)—NH₂ or a divalent                —(CH₂)_(t)— group which forms, with a neighbouring                nitrogen atom, a ring comprising 6 atoms,        -   x, y, z and t vary from 1 to 5, preferably x=y=z=t=2,        -   n is equal to 1, 2, 3 or 4,    -   R₁ is a hydrogen atom or a C₁ to C₅ hydroxyalkyl group,        preferably a hydroxyethyl group.

Mention may be made, as examples of such amines, of monoethanolamine,diethanolamine, urea, diethylenetriamine (DETA), triethylenetetramine(TETA), tetraethylenepentamine (TEPA), pentaethylenehexamine (PEHA),aminoethyltriethylenetetramine (AETETA),N″-(aminoethyl)tetraethylenepentamine andN′-(aminoethyl)tetraethylenepentamine (AETEPA), bis(piperazine)ethylene(BISPIP), aminoethylpiperazinylethylethylenediamine (AEPEEDA),piperazinylethyldiethylenetriamine (PEDETA),aminoethylpiperazinylethyldiethylenetriamine (AEPEDETA),piperazinylethyltriethylenetetramine (PETETA),tris(aminoethyl)aminoethylpiperazine (TRISAEAEP) andpiperazinylethylaminoethyldiethylenetriamine (PEAEDETA).

Preferably, the amine is urea, diethylenetriamine (DETA),triethylenetetramine (TETA), tetraethylenepentamine (TEPA) and themixtures of abovementioned amines in which TEPA is predominant, andadvantageously TEPA and the abovementioned mixtures.

The term “compound comprising activated ethylenic unsaturation(s)” isunderstood to mean a compound which includes at least one system offollowing formula (III):

The preferred compound comprising activated ethylenic unsaturation(s)corresponds to the following formula (IV):

in which:

-   -   R₃ represents a hydrogen atom, a C₁-C₅, preferably C₁-C₂, alkyl        group, a hydroxyl group or a C₁-C₅, preferably C₁-C₂, alkoxy        group,    -   R₄ and R₅, which are identical or different, represent a        hydrogen atom, a C₁-C₅, preferably C₁-C₂, alkyl group or a        —CO—R₃ group,    -   R₆ represents a hydrogen atom or a hydrocarbon chain which can        include one or more heteroatoms, in particular O, S, N and P,        especially a C₂-C₅, preferably C₂, carboxyalkylene radical.

The compounds comprising activated ethylenic unsaturation(s) which areparticularly preferred are acrylic acid, methacrylic acid, crotonicacid, fumaric acid, maleic acid, citraconic acid, itaconic acid and theanhydrides of these acids.

The amount of amine in the composition is such that the molar ratio ofthe compound comprising activated ethylenic unsaturation(s) to the aminevaries from 1 to 3.5, preferably from 1.5 to 3 and advantageously from 2to 2.5.

In the same way, the amount of compound comprising activated ethylenicunsaturation(s) in the composition is such that the molar ratio of thiscompound to the sum of the constituent saccharide units of thenon-reducing sugar varies from 0.05 to 1.5, preferably from 0.1 to 1.3and advantageously from 0.2 to 1.1. In the present case, the molar massof the corresponding saccharide compound is taken as molar mass of eachsaccharide unit.

The sizing composition can comprise, in addition to the compoundsmentioned, the conventional additives below in the followingproportions, calculated on the basis of 100 parts by weight of reducingsugar, inorganic acid metal salt, amine and compound comprisingactivated ethylenic unsaturation(s):

-   -   from 0 to 2 parts of silane, in particular an aminosilane,    -   from 0 to 20 parts of oil, preferably from 4 to 15 parts,    -   from 0 to 5 parts of a silicone,    -   from 0 to 30 parts of an “extender”.

The role of the additives is known and briefly restated: the silane isan agent for coupling between the fibres and the binder, and also actsas anti-ageing-agent; the oils are dust-preventing and hydrophobicagents; the silicone is a hydrophobic agent having the role of reducingthe absorption of water by the insulating product; the “extender” is anorganic or inorganic filler, soluble or dispersible in the sizingcomposition, which makes it possible in particular to reduce the cost ofthe sizing composition.

The sizing composition exerts a pH which varies according to the natureof the inorganic acid metal salt and the compound comprising activatedethylenic unsaturation(s) which are used, but it is generally at mostequal to 9 and advantageously varies from 3 to 7.

The various constituents present in the sizing composition react underthe effect of heat to form a polymeric network which constituents thefinal binder. When the temperature increases, the inorganic acid metalsalt brings about dehydration of the reducing sugar, which is reflectedby the appearance of at least two conjugated ethylenic bonds, thesebonds reacting with the other constituents of the sizing composition, inparticular with the compound comprising activated ethylenicunsaturation(s) and/or another dehydrated reducing sugar. The polymernetwork thus formed makes it possible to establish bonds between themineral fibres, in particular at the junctions of the fibres in themineral wool, which confers a degree of “elasticity” on the finalproduct capable of ensuring in particular good thickness recovery afterthe product has been unpacked.

The sizing composition according to the invention is intended to beapplied to fibres which can be mineral or organic, or also to a mixtureof mineral and organic fibres.

As already indicated, the mineral fibres can be glass fibres, inparticular fibres of E, C, R or AR (alkali-resistant) glass, or rockfibres, in particular of basalt (or wollastonite). These fibres can alsobe fibres including 96% by weight of silica and ceramic fibres based onat least one oxide, nitride or carbide of metal or semimetal, or on amixture of these compounds, in particular on at least one oxide, nitrideor carbide of aluminium, zirconium, titanium, boron or yttrium.

The organic fibres can be synthetic fibres or natural fibres.

Mention may be made, as examples of synthetic fibres, of fibres based onan olefin, such as polyethylene and polypropylene, on a polyalkyleneterephthalate, such as polyethylene terephthalate, or on a polyester.

Mention may be made, as examples of natural fibres, of plant fibres, inparticular fibres of wood, cellulose, cotton, coconut, sisal, hemp orflax, and animal fibres, in particular wool.

As already mentioned, the sizing composition is more particularly usedas sizing composition for thermal and/or acoustic insulation productsbased on mineral wool.

Conventionally, the sizing composition is applied to the mineral fibresat the outlet of the fiberizing device and before they are collected onthe receiving member in the form of a web of fibres which issubsequently treated at a temperature which makes possible thecrosslinking of the size and the formation of an infusible binder. Thecrosslinking of the size according to the invention takes place at atemperature of the order of 100 to 200° C., generally at a temperaturecomparable to that of a conventional formaldehyde-phenol resin, inparticular of greater than or equal to 110° C., preferably of less thanor equal to 170° C.

The products based on fibres sized using the composition, in particularthe acoustic and/or thermal insulating products obtained from thesesized fibres, also constitute a subject-matter of the present invention.

These products are generally provided in the form of a mat, a felt,panels, blocks, shells or other moulded forms based on mineral wool, ofglass or of rock.

The sizing composition can also be used to manufacture coated orimpregnated fabrics or veils (also known as “nonwovens”), in particularbased on mineral fibres, such as fibres of glass or of rock.

The veils of mineral fibres are used in particular as surface coatingfor thermal and/or acoustic insulating products based on mineral wool ora foam.

Another subject-matter of the invention is a process for the manufactureof a thermal and/or acoustic insulating product based on mineral wool orof a veil of mineral fibres, according to which the mineral wool or themineral fibres is/are manufactured, a composition according to theinvention is applied to the said wool or the said fibres and the saidwool or the said fibres is/are treated at a temperature which makespossible the crosslinking of the size and the formation of an infusiblebinder, for example under the thermal conditions described above.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 shows the variation in the modulus of elasticity E′ as a functionof temperature in accordance with an embodiment.

The size can be applied by any appropriate means, for example byprojection, spraying, atomization, coating or impregnation.

The following examples make it possible to illustrate the inventionwithout, however, limiting it.

In these examples, the following are measured:

-   -   the crosslinking start temperature (T_(C)) by the Dynamic        Mechanical Analysis (DMA) method, which makes it possible to        characterize the viscoelastic behaviour of a polymeric material.        The procedure is as follows: a sample of Whatman paper is        impregnated with the sizing composition (content of organic        solids of the order of 30%) and is then fixed horizontally        between two jaws. An oscillating component equipped with a        device for measuring the stress as a function of the strain        applied is positioned on the upper face of the sample. The        device makes it possible to calculate the modulus of elasticity        E′. The sample is heated to a temperature varying from 20 to        250° C. at the rate of 4° C./min. The curve of variation in the        modulus of elasticity E′ (in MPa) as a function of the        temperature (in ° C.) is plotted from the measurements, the        general appearance of the curve being given in FIG. 1. The value        of the crosslinking start temperature (T_(C)), in ° C., is        determined on the curve.    -   the tensile strength according to Standard ASTM C 686-71T on a        sample cut out by stamping from the insulating product. The        sample has the shape of a torus with a length of 122 mm, a width        of 46 mm, a radius of curvature of the cut-out of the outer edge        equal to 38 mm and a radius of curvature of the cut-out of the        inner edge equal to 12.5 mm.

The sample is positioned between two cylindrical mandrels of a testmachine, one of which is movable and is moved at a constant rate. Thebreaking force F (in newtons) of the sample is measured and the tensilestrength TS, defined by the ratio of the breaking force F to the weightof the sample, is calculated (N/g).

The tensile strength is measured after manufacture (initial tensilestrength) and after accelerated ageing in an autoclave at a temperatureof 105° C. under 100% relative humidity for 15 minutes (TS 15).

-   -   the initial thickness of the insulating product and the        thickness after compressing for 1 hour and 30 days with a degree        of compression (defined as being the ratio of the nominal        thickness to the thickness under compression) equal to 4.8/1.        The thickness measurements make it possible to evaluate the        dimensional behaviour of the product.    -   the thermal conductivity coefficient λ according to Standard EN        13162, expressed in W/(m×K).

EXAMPLES 1 TO 26

Sizing compositions are prepared which comprise the constituentsappearing in Table 1, expressed as parts by weight:

a) the compound comprising activated ethylenic unsaturation(s) and theamine are mixed beforehand in a first container and the mixture is leftat a temperature of the order of 20 to 25° C. for 15 minutes,

b) the sizing compositions are prepared by introducing, into a secondcontainer containing water, the reducing sugar, the inorganic acid metalsalt and the mixture obtained in a) with stirring until the constituentsare completely dissolved.

The performance of a sizing composition comprising 82 parts by weight ofa phenol-formaldehyde-monoethanolamine resin (Example 1 of WO2008/043960) and 20 parts by weight of urea (Ref.) is also shown inTable 1.

Examples 8, 11, 12 15, 20 and 26 exhibit lower crosslinking starttemperatures than the reference. However, the highest crosslinking starttemperatures (Examples 10, 24 and 25) remain acceptable.

The examples using fructose (Examples 16 and 17) are very similar tothose using glucose (Examples 1 and 8, respectively) with regard to thecrosslinking start temperature.

Zinc sulphate (Example 15) makes it possible to reduce the crosslinkingstart temperature more effectively than iron(II) sulphate (Example 12)or copper sulphate (Example 8), and better still than aluminium sulphate(Example 1).

EXAMPLES 27 TO 33

These examples illustrate the manufacture of insulating products on anindustrial line.

The sizing compositions of Examples 1 to 3 and the reference size (Ref.)are used to form products based on mineral wool exhibiting a nominaldensity equal to 17.5 kg/m³ and a thickness equal to 75 mm. The contentof binder (crosslinked size) represents 4.7% by weight of the product.

The sizing compositions A, B and C, comprising the followingconstituents (in % by weight), are also used:

A B C Glucose 75.1  75.1  75.1  Aluminium sulphate 7.4 — — Coppersulphate — 7.4 — Iron(II) sulphate — — 7.4 Tetraethylenepentamine(TEPA)⁽¹⁾ 8.5 8.5 8.5 Maleic anhydride 9.0 9.0 9.0

Glass wool is manufactured on a pilot-scale line by the internalcentrifugation technique in which the molten glass composition isconverted into fibres by means of a tool, referred to as centrifugingdisc, comprising a basket forming a chamber for receiving the moltencomposition and a peripheral band pierced by a multitude of orifices:the disc is rotated about its vertically positioned axis of symmetry,the composition is ejected through the orifices under the effect of thecentrifugal force and the material escaping from the orifices is drawninto fibres with the assistance of a drawing gas stream.

Conventionally, a size spraying ring is positioned beneath thefiberizing disc so as to uniformly distribute the sizing compositionover the glass wool which has just been formed.

The mineral wool, thus sized, is collected on a belt conveyor with awidth of 2.4 m equipped with internal extraction boxes which hold themineral wool in the form of a web at the surface of the conveyor. Theweb passes continuously through an oven maintained at 270° C., where theconstituents of the size polymerize to form a binder. The amount ofbinder represents 4.7% by weight of the final insulating product.

The properties of the insulating products appear in Table 2.

The properties of the product are better when the sizing compositioncomprises a greater proportion of TEPA and maleic anhydride (Examples 27to 29). The product of Example 27 is very close to that of thereference.

The properties of the product are better with copper sulphate (Example30) than with aluminium sulphate (Example 31) and iron(II) sulphate(Example 32).

EXAMPLES 34 TO 41

These examples illustrate the manufacture of other insulating productson a pilot-scale line.

The sizing compositions having the constituents appearing in Table 3 andthe reference size (Ref.) are used to form products exhibiting a nominaldensity equal to 10.6 kg/m³ and a thickness equal to 144 mm. The contentof binder (crosslinked size) represents 4.7% by weight of the product.

The mineral wool is obtained under the conditions of Examples 27 to 33modified in that it is cut up before being introduced into an oven at210° C. for 5 minutes and then the mineral wool is again placed in theoven, after having been turned upside down, for an additional 5 minutes.

The properties of the insulating products appear in Table 3.

The decrease in the amount of TEPA and maleic anhydride in the sizingcomposition reduces the product performance (Examples 36 to 38).

Aluminium sulphate (Example 36) is equivalent to copper sulphate(Example 39), but this tendency is reversed when the amount of TEPA andmaleic anhydride is reduced (Examples 38 and 40).

EXAMPLES 42 TO 45

The procedure is carried out under the conditions of Examples 1 to 26,modified in that the sizing compositions comprise the constituentsappearing in Table 4, expressed as parts by weight.

Examples 42 and 43 according to the invention exhibit a much lowercrosslinking start temperature than the corresponding ComparativeExamples 44 and 45, lower by 30 and 48° C. respectively.

The crosslinking start temperature of Example 45 is not compatible withthe manufacturing conditions in an industrial line as it is far toohigh.

TABLE 1 Example 1 2 3 4 5 6 7 8 9 10 11 Ref. Sizing composition Glucose64.0 76.0 85.5 68.0 76.6 64.0 64.0 64.0 76.0 85.5 62.0 — Fructose — — —— — — — — — — — — Aluminium sulphate  3.0  4.0  4.5 12.0 13.4  3.0  3.0— — — — — Copper sulphate — — — — — — —  3.0  4.0  4.5 10.0 — Iron(II)sulphate — — — — — — — — — — — — Zinc sulphate — — — — — — — — — — — —Tetraethylenepentamine (TEPA)⁽¹⁾ 16.2  9.8  4.9  9.8  4.9 18.6 14.4 16.2 9.8  4.9 13.7 — Triethylenetriamine (TETA) — — — — — — — — — — — —Priamine ®⁽²⁾ — — — — — — — — — — — — Monoethanolamine — — — — — — — — —— — — Diethanolamine — — — — — — — — — — — — Urea — — — — — — — — — — —— Maleic anhydride 16.8 10.2  5.1 10.2  5.1 14.4 18.6 16.8 10.2  5.114.7 — Itaconic acid — — — — — — — — — — — — Citraconic anhydride — — —— — — — — — — — — Fumaric acid — — — — — — — — — — — — PropertiesCrosslinking start temp. T_(c) (° C.) 145   152   162   154   164  152   141   133   155   170   135   151   pH⁽³⁾  4.5  4.1  3.8 n.d. n.d. 7.4  4.4  4.1  4.0  6.5  3.6  6.0 Example 12 13 14 15 16 17 18 19 20Ref. Sizing composition Glucose 64.0 68.0 76.6 64.0 — — 64.0 59.7 59.7 —Fructose — — — — 64.0 64.0 — — — — Aluminium sulphate — — — —  3.0 — 3.0  3.3  3.3 — Copper sulphate — — — — —  3.0 — — — — Iron(II)sulphate  3.0 12.0 13.4 — — — — — — — Zinc sulphate — — —  3.0 — — — — —— Tetraethylenepentamine (TEPA)⁽¹⁾ 16.2  9.8  4.9 16.2 16.2 16.2 16.216.0 16.0 — Triethylenetriamine (TETA) — — — — — — — — — — Priamine ®⁽²⁾— — — — — — — — — — Monoethanolamine — — — — — — — — — — Diethanolamine— — — — — — — — — — Urea — — — — — — — — — — Maleic anhydride 16.8 10.2 5.1 16.8 16.8 16.8 — — — — Itaconic acid — — — — — — — 21.0 — —Citraconic anhydride — — — — — — — — 21.0 — Fumaric acid — — — — — —16.8 — — — Properties Crosslinking start temp. T_(c) (° C.) 133   157  160   130   140   144   145   156   137   151   pH⁽³⁾  4.6 n.d. n.d. 4.9  4.0  4.0  4.2  5.2  5.1  6.0 Example 21 22 23 24 25 26 Ref. Sizingcomposition Glucose 63.4 39.7 44.1 28.6 37.1 64.0 — Fructose — — — — — —— Aluminium sulphate  3.0  3.0  3.0  1.0  2.0 — — Copper sulphate — — —— —  3.0 — Iron(II) sulphate — — — — — — — Zinc sulphate — — — — — — —Tetraethylenepentamine (TEPA)⁽¹⁾ — 24.3 — — — 12.1 — Triethylenetriamine(TETA) 14.6 — — — — — — Priamine ®⁽²⁾ — 10.4 21.5 — — — —Monoethanolamine — — — 27.4 — — — Diethanolamine — — — 30.8 — — Urea — —— 16.2 —  4.1 — Maleic anhydride 18.6 25.6 28.4 44.0 28.8 16.8 —Itaconic acid — — — — — — — Citraconic anhydride — — — — — — — Fumaricacid — — — — — — — Properties Crosslinking start temp. T_(c) (° C.)141   129   142   174   170   137   151   pH⁽³⁾  3.8  3.0  3.0  2.7  3.0 2.9  6.0 ⁽¹⁾Sold by Huntsman (mixture of TEPA (predominant), AETETA,AEPEEDA, PEDETA and BISPIP) ⁽²⁾Sold by CRODA under the reference 1074(C₃₆ amine dimer) ⁽³⁾solids content: 30% n.d.: not determined

TABLE 2 Example 33 27 28 29 30 31 32 (comparative) Sizing compositionEx. 1 Ex. 2 Ex. 3 A B C Ref. Properties Tensile strength (N/g) Initial4.0 3.1 2.3 2.7 3.3 2.4 4.5 After ageing (TS 15) 3.4 3.0 2.2 2.3 3.0 2.43.8 Thickness (mm) After 1 hour 82.0 81.8 82.9 80.6 80.1 80.4 82.5 After30 days 76.6 77.6 82.2 75.9 75.5 75.9 77.2 λ (W/(m × K)) 0.034 0.0340.034 0.034 0.034 0.034 0.034

TABLE 3 Example 41 34 35 36 37 38 39 40 (comparative) Sizing compositionEx. 4 Ex. 5 Ref. Glucose 65.0 61.0 60.5 68.0 76.6 60.5 76.6 — Aluminiumsulphate  3.0 — 10.7 12.0 13.4 — — — Copper sulphate — 10.0 — — — 10.713.4 — Tetraethylenepentamine (TEPA)⁽¹⁾ 14.0 12.6 14.1  9.8  4.9 14.1 4.9 — Maleic anhydride — — 14.7 10.2  5.1 14.7  5.1 — Maleic acid 17.015.4 — — — — — — Properties Tensile strength (N/g) Initial  3.0  2.6 2.5  1.9  1.4  2.5  2.1  3.7 After ageing (TS 15)  2.6  2.2  2.1  1.8 1.5  2.1  1.4  3.3 Thickness (mm) After 1 hour 145.9  151.2  142.9 142.7  146.1  140.3  139.7  143.2  After 30 days 99.9 n.d. n.d. 108.7 108.4  101.0  95.5 109.8  ⁽¹⁾Sold by Huntsman (mixture of TEPA(predominant), AETETA, AEPEEDA, PEDETA and BISPIP) n.d.: not determined

TABLE 4 Example 44 45 42 43 (comp.) (comp.) Sizing composition Glucose57 76 57 76 Copper sulphate 10 14 0.28 0.38 Tetraethylenepentamine(TEPA) 16.2 4.9 16.2 4.9 Maleic anhydride 16.8 5.1 16.8 5.1 PropertiesCrosslinking start temp. T_(c) (° C.) 145 148 175 196 pH 3.3 3.0 4.0 4.5

The invention claimed is:
 1. Formaldehyde-free sizing composition forfibres, comprising: at least one reducing sugar, copper sulphate, atleast one amine selected from the group consisting of monoethanolamine,diethanolamine, diethylenetriamine (DETA), triethylenetetramine (TETA),tetraethylenepentamine (TEPA), pentaethylenehexamine (PEHA),aminoethyltriethylenetetramine (AETETA),N″-(aminoethyl)tetraethylenepentamine andN′-(aminoethyl)tetraethylenepentamine (AETEPA), bis(piperazine)ethylene(BISPIP), aminoethylpiperazinylethylethylenediamine (AEPEEDA),piperazinylethyldiethylenetriamine (PEDETA),aminoethylpiperazinylethyldiethylenetriamine (AEPEDETA),piperazinylethyltriethylenetetramine (PETETA),tris(aminoethyl)aminoethylpiperazine (TRISAEAEP) andpiperazinylethylaminoethyldiethylenetriamine (PEAEDETA), and mixturesthereof, and at least one compound comprising activated ethylenicunsaturation(s), the copper sulphate being present in an amount at leastequal to 1% of the weight of the reducing sugar.
 2. Compositionaccording to claim 1, wherein the reducing sugar is an oligosaccharideincluding from 1 to 10 saccharide units.
 3. Composition according toclaim 2, wherein the reducing sugar is glucose, galactose, mannose,fructose, lactose, maltose, isomaltose or cellobiose.
 4. Compositionaccording to claim 3, wherein the reducing sugar is glucose or fructose.5. Composition according to claim 1, wherein the amount of coppersulphate represents from 1 to 30% of the weight of the reducing sugar.6. Composition according to claim 1, wherein the amine isdiethylenetriamine (DETA), triethylenetetramine (TETA),tetraethylenepentamine (TEPA) and mixtures of abovementioned amines inwhich TEPA is predominant.
 7. Composition according to claim 1, whereinthe compound comprising activated ethylenic unsaturation(s) correspondsto the following formula (IV):

in which: R₃ represents a hydrogen atom, a C₁-C₅ alkyl group, a hydroxylgroup or a C₁-C₅ alkoxy group, R₄ and R₅, which are identical ordifferent, represent a hydrogen atom, a C₁-C₅ alkyl group or a —CO—R₃group, R₆ represents a hydrogen atom or a hydrocarbon chain which caninclude one or more heteroatoms.
 8. Composition according to claim 7,wherein the compound is acrylic acid, methacrylic acid, crotonic acid,fumaric acid, maleic acid, citraconic acid, itaconic acid and theanhydrides of these acids.
 9. Composition according to claim 1, whereinthe amount of amine in the composition is such that a molar ratio of thecompound comprising activated ethylenic unsaturation(s) to the aminevaries from 1 to 3.5.
 10. Composition according to claim 1, wherein theamount of compound comprising activated ethylenic unsaturation(s) in thecomposition is such that a molar ratio of the compound to the sum of theconstituent saccharide units of the reducing sugar varies from 0.05 to1.5.
 11. Composition according to claim 1, further comprising theadditives below in the following proportions, calculated on the basis of100 parts by weight of reducing sugar, copper sulphate, amine andcompound comprising activated ethylenic unsaturation(s): from 0 to 2parts of silane, from 0 to 20 parts of oil, from 0 to 5 parts of asilicone, from 0 to 30 parts of an extender.